Project brief: Install a Vacuum Tube system and see how it performs against the existing Flat Plate systems

another successful installation in the kalahari desert, at the luxurious Tswalu Private Game Lodge, where the rolling folds of scorched earth could use a little of the shade produced by a solar array.

It certainly doesnt seem like a desert. Our room is a 3 star semi detached unit, it has wifi and 3 cooked meals a day in the lounge room and little barfridge that never runs out of cooldrink. No. No beers. But beyond the gates of the Tswalu game resort contractors' base camp, it is arid, dry, and other parched adjectives, and a sense of being microwaved from on high. Base camp is a bubble well clung to with hope, because if you went and stood on that little hill over there, you'd see the same dry tundra in all directions. We literally did follow the Eskom electricity cables for miles into the resort - literally the only connection to the outside world, except for those little mobile phone signal boosters that do try so very hard.

But we didn't install any solar electric, this trip was a standard 200 litre solar hot water system from local brand Nupower. It's a 24 tube, vacuum-tube array, with an intelligent controller, solar panel, blah blah, the full monty. The mission is to pit the pumped vacuum tube technology against the existing flat plate thermosyphon, which apparently is not doing the job. We are most excited with the challenge, as of course it's a winner, more than likely for the intelligence of the digital controller that comes standard with the vacuum tube installation.

Desert conditions are fabulous in the early morning and early evening, every other time, it becomes really cold or really hot. Many plumbing installions struggle in these wildly contradicting circumstances, and the flat plate solar collectors are a particular delicacy for this monstrous gremlin, because if it gets to pry open one just one of the fittings by expansion and contraction, then it can possibly cause a complete failure of the system.

On the other hand, the vaccum tube collector operates within a certain pre-defined temperature range that not only heats the water, but will also sacrifice hot water to make sure the collector stays within this range, how does it do that? by pumping some of the hot water thru the collector should it start getting a bit cold - a very important feature, as the desert can literally get down and dirty to -11 degrees (minus eleven)!